1. Field of the Invention
This invention relates generally to a process of producing purified gamma- and/or delta-tocotrienols from tocol-rich oils or distillates, and more particularly to a process of producing a gamma- and/or delta-tocotrienol-rich fraction or extract from rice bran oil deodorizer distillate, palm oil or other tocol-rich oil or distillate.
2. Description of the Related Art
Rice bran oil (RBO) is generally produced by extracting oil from the heat stabilized rice bran, either by hydraulic pressing or solvent extraction. Crude RBO goes through a series of refining steps, including degumming, neutralization, bleaching, dewaxing, winterization and deodorization. Deodorization employs high heat steam distillation to remove volatile compounds that could give RBO undesirable flavor or odor. Unsaponifiables, such as vitamin E and sterols, are also removed from the oil resulting in deodorizer distillate with a high level of these compounds. Up to 90% of the tocotrienols present in rice bran may be lost to the deodorizer distillate during the refining process.
Additionally, tocotrienol-rich fractions or concentrates have been prepared from palm oil sources. Commercial tocotrienol rich fractions (TRF) isolated from palm oil contain about 20 to 30% tocols of which gamma tocotrienol accounts for about half, and alpha tocopherol accounts for about 20%.
Vitamin E is a family made up of eight major lipid-soluble antioxidants: d-α-tocopherol (α-T), d-β-tocopherol (β-T), d-γ-tocopherol (γ-T), d-δ-tocopherol (δ-T), d-α-tocotrienol (α-T3), d-β-tocotrienol (β-T3), d-γ-tocotrienol (γ-T3) and d-δ-tocotrienol (δ-T3). Tocopherols and tocotrienols, collectively called tocols, have a 6-chromanol ring at the base of their structure with a hydrocarbon chain at the 2-position. The structures of these vitamin E groups differ only in the degree of saturation of their hydrophobic tail, with tocopherols being fully saturated and tocotrienols containing three double bonds. α-, β-, γ- and δ-tocols are characterized by the number and position of methyl substituents on the aromatic ring.
α-T is the only vitamin E compound to meet dietary vitamin E requirements due to its preferential retention in the body by hepatic α-T transfer protein (α-TTP). All tocols, however, have antioxidant activity and may protect against oxidative stress, which has been linked to many diseases, such as cancer, cardiovascular disease, diabetes, neurodegenerative diseases (e.g., Alzheimer's, Parkinson's), among others. Rice bran (RB) and RBO consumption has been shown to reduce cholesterol in numerous studies in which the hypocholesterolemic ability of RB products is due to the unsaponifiable content, specifically tocotrienols, including γ-T3, and their ability to inhibit HMG-CoA reductase, the rate-limiting enzyme in cholesterol biosynthesis. Tocotrienols have also been shown to have much more potent antiproliferative and apoptotic effects on carcinogenic cells than tocopherols. γ-T3 and δ-T3 are generally considered to be the strongest anti-carcinogenic agents of the tocol family.
In addition, tocols, especially γ-T3, have been shown to have the ability to act as radiation countermeasures, and several studies have been conducted to investigate the degree to which γ-T3 ameliorates radiation injury. Treatment with γ-T3 in irradiated mice resulted in increased survival rates, improved hematopoietic recovery and reduced vascular oxidative stress caused by irradiation. It has also been suggested that δ-T3 may also provide some significant radioprotective potential. Outside of emergency nuclear situations, the radioprotective effects of γ-T3 and δ-T3 may be useful in therapy for radiation treatments in cancer patients as well; however, co-administration of α-T has been shown to cause interference with the hypocholesterolemic and anti-carcinogenic effects of γ-T3 and δ-T3, and may adversely affect the radioprotective properties of γ-T3.
Several methods have been proposed to recover tocols from vegetable oil refining by-products including; distillation, supercritical carbon dioxide, and solvent fractionation in combination with a cold crystallization step, but these methods do not result in satisfactory isolation/purification of individual tocols including gamma or delta-tocotrienol. Flash chromatography has been used for fractionation of mixtures, employing short columns packed with intermediate size particles (40-60 μm) with accelerated solvent flow achieved by modest pressure. Flash chromatography has been used to isolate a tocol rich fraction from rice bran, with diethyl ether as elution solvent, but the usage of ether poses serious safety hazards. Others have used a diol column and a linear gradient of increasing isopropanol in hexane to purify tocopherols from corn and soybean oils. Yet another method for separating tocotrienols from a tocol-containing mixture involves a combination of heating, distillation, and series of solvent partitioning steps, but the method does not result in high purity of gamma-tocotrienol. None of these prior methods, however, separate individual tocols, including gamma- and/or delta-tocotrienol.
It is therefore desirable to provide a process of producing purified gamma- and delta-tocotrienols from tocol-rich oils or distillates.
It is further desirable to provide a process of producing a gamma- and/or delta-tocotrienol-rich fraction from tocol-rich oils or distillates that results in a high proportion of γ-T3 and/or δ-T3 while minimizing the presence of alpha isomers from the tocol-rich oils or distillates.
It is yet further desirable to provide a process of producing purified γ-T3 and/or δ-T3 from tocol-rich oils or distillates that does not use toxic solvents, such as ether, and that uses much less organic solvent than semi-preparative HPLC, resulting in a cheaper and more environmentally friendly process.
It is still further desirable to provide a process of producing a γ-T3 and/or δ-T3-rich fraction from tocol-rich oils or distillates where gamma- and/or delta-tocotrienol comprises about 95% of total tocols, with a gamma-tocotrienol yield of approximately 10% and/or a delta-tocotrienol yield of about 3%, and with purity in excess of about 95%.
It is further desirable to provide a process of producing a gamma- and/or delta-tocotrienol-rich fraction from tocol-rich oils or distillates using a fast flash or low pressure liquid chromatography.
It is further desirable to provide a γ-T3- and/or δ-T3-rich extract for use as an antioxidant ingredient in lipid-containing foods (e.g., pet foods), cosmetics, personal care products, vitamin supplements, pharmaceuticals and/or nutraceuticals.
It is further desirable to provide a γ-T3- and/or δ-T3-rich extract that can be incorporated into a highly purified γ-T3- and/or δ-T3-tocotrienol or a γ-T3- and/or δ-T3-tocotrienol-rich product for use in the medical field as a radio-protective compound, i.e., given to cancer patients undergoing radiation treatment, sold as a dietary supplement, and/or used by individuals exposed to radiation poisoning as a result of a nuclear accident or terrorist activity.
Other advantages and features of the invention will be apparent from the following description and from the claims.